A Pennsylvania judge on Thursday granted convicted child molester Jerry Sandusky a hearing later this month to press his case for a new trial, four years after the former Penn State University football coach was found guilty of abusing 10 boys.

Lawyers for Sandusky can pursue several issues at the May 20 hearing, including the competency of his trial attorney, whether prosecutors and the judge who oversaw the grand jury withheld evidence and whether the state attorney general's office leaked sealed grand jury material to a reporter in an effort to persuade additional victims to come forward.

John Cleland, a visiting judge in the Centre County Court of Common Pleas in Bellefonte, Pennsylvania, had expressed skepticism regarding Sandusky's appeal during a court appearance on Monday but nevertheless ordered the evidentiary hearing.

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"We're just going to prepare for the hearing," said Alexander Lindsay, Sandusky's current lawyer. "We're formulating our witness list now."

Representatives for the attorney general's office could not immediately be reached for comment.

Sandusky, 72, is serving 30-60 years in state prison after a jury convicted him in 2012 of molesting 10 boys at Penn State sports facilities or through the auspices of The Second Mile, his former charity.

He has already lost several previous appeals. The current claims were brought under the state's post-conviction relief act, which allows appeals based on ineffective legal counsel and constitutional violations, among other grounds.

To win a new trial, the defense must prove both that there was a violation of Sandusky's right to a fair trial, and that the violation created a "reasonable probability" of a different outcome, said Peter Goldberger, a lawyer in Philadelphia who specializes in appeals and is not involved in this case.

Lindsay has accused prosecutors and the judge who supervised the grand jury that investigated Sandusky of failing to turn over evidence that might have helped his defense.

He will also seek to prove that prosecutors in the attorney general's office in 2011 leaked secret grand jury information to Harrisburg Patriot-News reporter Sara Ganim in the hopes that other alleged victims of Sandusky would emerge.

At Monday's hearing, Cleland gave Lindsay permission to call Attorney General Kathleen Kane to testify whether she believes such a leak occurred.